Warplanes and helicopters roared over Ankara and explosions could be heard there. Reuters reporters saw a helicopter open fire. State-run news agency Anadolu said military helicopters had fired on the headquarters of the intelligence agency.
Reuters journalists saw tanks open fire near the parliament building in Ankara, which they had surrounded.
Airports were shut, access to Internet social media sites was cut off, and troops sealed off the two bridges over the Bosphorus in Istanbul, one of which was still lit up red, white and blue in solidarity with victims of the Bastille Day truck attack in France a day earlier.
Soldiers took control of TRT state television, which announced a countrywide curfew and martial law. An announcer read a statement on the orders of the military that accused the government of eroding the democratic and secular rule of law. The country would be run by a "peace council" that would ensure the safety of the population, the statement said.
TRT later went off the air.
Anadolu said the chief of Turkey's military staff was among people taken "hostage" in the capital Ankara. CNN Turk also reported that hostages were being held at the military headquarters.
NOT A TINPOT COUP
A senior EU source monitoring the situation said: "It looks like a relatively well orchestrated coup by a significant body of the military, not just a few colonels. They've got control of the airports and are expecting control over the TV station imminently. They control several strategic points in Istanbul.
"Given the scale of the operation, it is difficult to imagine they will stop short of prevailing. It's not just a few colonels," the source repeated.